mineral

Moss Agate

Silicon Dioxide (SiO2) with inclusions of manganese or iron oxide

Hardness: 6.5-7 on Mohs scale. Color: Clear to milky white chalcedony with green, red, or brown dendritic inclusions. Luster: Vitreous to waxy. Crystal Structure: Hexagonal (trigonal) microcrystalline silica.

Hardness: 6
Luster: Vitreous to waxy

Identified January 7, 2026More mineral →

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Physical properties

Formation & geological history

Formed through the weathering of volcanic rocks where silica-rich groundwater fills cavities and cracks. The 'moss' patterns are formed by dendritic growths of manganese and iron oxides during the crystallization process. Ages vary by deposit but often found in Cenozoic volcanic regions.

Uses & applications

Used primarily in jewelry as cabochons, for lapidary art, as decorative carvings, and in metaphysical collecting. Historically used by farmers as a 'luck stone' for healthy crops.

Geological facts

Despite the name, Moss Agate does not contain organic matter; the patterns are purely mineral. It is often called the 'Mocha Stone' due to historical trade through the Yemeni port of Mocha.

Field identification & locations

Identify by its translucent body combined with branching, moss-like inclusions that are trapped within the stone. Commonly found in India, Brazil, Uruguay, and the western United States (Montana Moss Agate is highly prized). In the field, look for a waxy luster on fractured surfaces and a high resistance to scratching.

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